急救成功的关键是胆大心细，操作正确。
参考答案：原题中：胆大心细，应改为：动作快
As a rule, you can borrow only two books ______ in the library.
A．at one time
B．at a time
C．in no time
D．at times
在转轴上装配D型及V型密封圈时应注意哪些事项？
